The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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Failure Analysis of a PEX Piping Crimp System
Premature failures have occurred in some PEX piping systems that utilized a stainless steel crimp ring to attach the PEX pipe to copper or brass fittings. Leaks in these systems were traced to a non-uniform crimping of the PEX tubing around the circumference of the fittings. Some leaks were also due to cracking of the crimp rings as a result of the crimping process and corrosion of the rings.
Flow Field Simulation of the Modular VCR in Continuous Mixer
VCR (Various clearance rotor) is a new type of continuous mixer’s modular rotor. The flow field of different configurations flow field of VCR has been simulated in this paper. According to the simulation result, the pressure, velocity and viscosity field are obtained. The average shear stress, shear rate and shear degree in deferent configurations are calculated by post-process program. Meanwhile, the mixing ability of different configurations flow field is compared.
The Effect of Process Conditions on Part Quality in Microinjection Molding
Micromolded parts produced using a range of injection velocities, mold temperatures, melt temperatures, and hold conditions were examined for part quality. Part dimensions were measured using an optical comparator and residual stresses were evaluated under polarized light. Results are discussed in terms of the material properties and processing conditions.
Statistical Approach to Evaluate Composite Damage (Design of Experiment and Evaluation)
The objective of this research is to develop a methodology for combined mechanical and thermal synergistic test for M40J/PMR-II-50 [90/0]s, a uni-tape composite material; and its analysis by using a statistical approach. Four different controlled factors (mechanical strain, temperature range of thermal cycling, number of thermal cycles, and heating rate), which degrade the composite, are evaluated in terms of both primary effects and interaction effects quantitatively.
A Study of Micro Injection Molding Optical Fiber Ferrules
This study focused on plastic micro injection molding optical fiber ferrules. Each ferrule has a through hole in the center. The inner diameter is 125±1?m. How to keep the micro core pin at the center becomes a critical issue. A guiding mechanism is introduced to reduce the chance of pin’s mis-alignment and increase life time. The design concept of presented guiding mechanism is also suitable for molding micro tubes, especially for high aspect ratio cases.
Properties of Injection Molded Amorphous Polymer for Punching
Deformation and crack-formation of holes during punching were investigated for injection molded polystyrene (PS) and polycarbonate (PC). Amount of deformation for both polymers increased with increasing punching temperature and with decreasing punching speed. The extent of deformation for both polymers were especially large when punching was conducted at temperatures above the glass transition temperature (Tg) of the polymers. For PS, two types of cracks appeared. However, only one type of crack appeared for PC.
Monte Carlo Modelling of LDPE on a Molecular Level; Relating Molecular Structure to Polymer Properties
Although LDPE is amongst the oldest polymers, it is also the polymer with one of the most complex molecular structures. Using a Monte Carlo method a model has been developed with which it is possible to calculate the detailed structure of each and every single molecule. The molecular characteristics have been related to analytical methods like GPC, NMR and DMS. Moreover the effects of the molecular structure on the polymer properties have been studied. The model has proven to be a valuable tool in product and process development.
Improvement of Mold Design: A New Method Based on Contradictions
Designing injection molds is of a critical issue in injection processing. In order to improve its design, we propose to focus on technical problems. We built and tested a design procedure based on technical problems mold design has to cope with. Using this procedure, design process duration is reduced; the mold cost and part quality might be improved.
The Role of Numerical Injection Molding Simulation in Predicting Mechanical Properties
Research objective is to establish manufacturing-related design rules and procedures for engineering design of injection molded thermoplastics parts, and to investigate application of novel materials to support development of design for sustainability. Outputs of numerical injection molding simulations have been compared with tensile and tensile-impact test results for different geometry-material combinations. Combination with simulation results on thick-walled parts reported earlier has led to a systematic with predictive capability of simulation outputs for differences in mechanical performance.
Vibration Welding Non-Planar Surfaces
This study examines the vibration welding of mating plates whose faying surface lies in two distinct planes. Plates containing both ‘horizontal’ and ‘angled’ surfaces were injection molded using a glass-fiber-reinforced nylon 6. These plates were then vibration welded to create a butt-welded assembly containing two non-parallel weldlines. The tensile weldline strengths were measured at different locations along the weld. Weld pressure, vibration direction with respect to the plate axis and the geometry of the ‘angled’ section were all observed to have significant effects on weld strength.
Molecular Reinforced Nano-Silicate Composites
It is well established that physical interactions at the polymer/reinforcement interface have a significant influence on the bulk response in nanocomposites. This paper presents results from studies where both the physical and chemical interactions at the interface are altered and related to the bulk mechanical properties of the nanocomposite. The results show that for optimum performance, both types of interactions must be considered.
Process Monitoring and Quality Prediction: A Task for the Entire Process Chain
Rising quality requirements and complexity mean that e.g. an injection molding machine can no longer be observed in isolation. It is becoming increasingly important to view the process chain in its entirety, starting with the material properties and proceeding via plastification, mold filling and cooling, right through to the downstream processes such as refinement and coating, or joining techniques. From this viewpoint for online process control, techniques are necessary that take into account every step of the production line.
Development and Characterization of Thermoplastic Biodegradable Nanocomposites
Biodegradable blends of amorphous Poly(lactic acid) (PLA) and polycaprolactone (PCL) have been developed by melt blending. The morphology of these materials was characterized by means of WAXD and TEM, showing that silicate layers of the kaolinite (chemically modified kaolinite) were intercalated and evenly distributed within the biodegradable matrix. Mechanical, thermal and gas barrier properties of the different blends and nanocomposites were studied and the effect of clay addition on the above-mentioned properties was evaluated.
The Effect of Blending LLDPE Comonomers with Conventional LDPE on the Thermal and Mechanical Properties of Packaging Films
The selection of the correct blend of LLDPE with conventional LDPE is critical when a specific performance property, such as heat seal strength, is required for a thin film application. Extruded blown films using different blends of LLDPE and conventional LDPE were produced. Thermal properties and mechanical properties were influenced by the type and percentage of LLDPE used.
Monitoring Surface Quality of Recycled UPVC Extrudate
Surface quality of profile extruded from recycled uPVC has been examined using a novel on-line visualization system and surface interferometry. A calibrated strip profile was extruded from various grades of recycled uPVC window frame. Surface defects were monitored using a high-frequency line-scan camera and categorised in terms of size, shape and position. Surface roughness was measured using a white light interferometer. PVC recovery method, batch variation and processing conditions were found to affect surface quality of the extrudate.
Rheometric Properties Based Model for an Improved Solid Contents CIM Feedstock
A new formulation for Ceramic Injection Molding (CIM), based on a high-grade alumina powder bound with a water debinding system, composed by a mixture of a low molecular weight polyethylene and a polyethylene glycol, has been developed.The present paper reports the determination of the critical powder concentration of the developed feedstock by rheological model fitting. Semiempirical models were discriminated in order to establish the optimum ceramic powder concentration window.
Injection Molding Variants: A Designer’S Review
The possibilities of plastics processing techniques based on injection molding are continuously expanding. For design engineers it is interesting but time consuming to stay up to date. A systematic approach is presented to classify existing and emerging technologies with respect to product requirements, to take the best advantage of new design opportunities.
Insights into Thermoset Behavior: John Gillham in Retrospect
John Gillham’s work in thermosetting polymers provided a paradigm for the time-temperature transformation characterization of these materials that is now the lens through which we look at their processing. I provide a retrospective and prospective for the insights provided by Gillham into thermoset behavior.
Volume Recovery and the Tau-Effective Paradox
Volume recovery experiments on polystyrene and on an epoxy glass have been made. The experiments on the polystyrene involved novel temperature perturbations which allowed us to obtain the relaxation time as a function of volume during aging. The experiments on the epoxy were performed to investigate the ?-effective paradox. Both sets of experiments indicate that the relaxation time does not depend on the instantaneous volume as assumed in models of structural recovery.
The Rotational Moulding Characteristics of Biodegradable Copolyesters
Biodegradable copolyesters are processed primarily through extrusion and injection moulding. This paper presents preliminary investigations into the grinding and rotational moulding characteristics of commercially available biodegradable copolyester. Cryogenic grinding and subsequent rotational moulding experiments on the copolyester resin resulted in complete mouldings of uniform wall thickness being produced. It was observed that peak internal mould air temperatures of approximately 150 degC are required in order to produce acceptable mouldings.
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